cyclones

A cyclones occurs when the pressure in some areas in the atmosphere, decreases into a consiberable extent. A pressure depression
is created where the pressure is decreased significantly than the atmospheric pressure.Then the air in the atmosphere isblown in a very high speed towards the pressure depression.
This causes a cyclone.Cyclones are limited to some oceans. It is because these oceans satisfy the necessary factors for cyclones.Cyclones in the bay of Bengal affect ourcountry directly as well as indirectly.
A develoved cyclone has a diameter about 100 km.Rains with storms and thunder bolts may occur due to cyclones.
Also,sea waves may rise up.Many animals and human lives are lost and the properties are destroyed by cyclones.
The centre area of a cyclo ne is known as the  ''eye''. The cyclone affects thousand of kilo metres from the ''eye''.  Usually the speed of the wind in areas with less pressure is less than 31 km per hour.
The speed of the wind in the areas with a deep pressure depression is 50-60 km  per hour.The speed of a   cyclone is 62-88 kilo metres per hour. The speed of a very strong cyclone is 89-117 km per hour. The speed of some cyclones is over 118 km  per hour.
In 1907, 1922, 1964, 1978, 1992, 2001 Sri Lanka experienced strong  cyclones. The strongest among them was the cyclone that occurred in 1978.